Motor vehicle fire extinguisher

ABSTRACT

A fire extinguishing system for the engine compartment of a motor vehicle in which a generally tubular container, filled with a synergistic mixture of an alkali metal or alkaline earth metal carbonate or bicarbonate and a synthetic metal silicate, is mounted in the compartment, preferably on a side wall or in the air cleaner, a dispersing means is mounted on one or both ends of the container, a propellant means, preferably including a gas impervious piston, a container of a pressurized gas and a springloaded puncturing means, is mounted in the container and a flameactuated ignition means, preferably composed of specific amounts of platinum or palladium in intimate contact with aluminum or magnesium, is operatively attached to the propellant means and disposed about the interior of the compartment.

United States Patent 1 1 Dunn [ 1 MOTOR VEHICLE FIRE EXTINGUISHER Byron G. Dunn, 6831 Orchid Ln., Dallas, Tex. 75230 22 Filed: Nov. 19,1973

2| App]. M0,; 416,871

- Related U.S. Application Data [63] Continuation-impart of Ser. No. 131,333, April 5, 1971, Pat. No. 3,773,111, and Ser. No. 400,623, Sept. 25, 1973, and Ser No. 400,640, Sept. 25, 1973.

[76] Inventor:

[52] U.S. Cl. 169/59; 169/62; 169/26; 169/33 [51] Int. Cl. A621: 35/12 [58] Field 01' Search 169/62, 5, 26, 9, 28, 46, 169/77, 56, 59, 33, 71

[56] References Cited UNlTED STATES PATENTS 1,067,803 7/1913 Daniel 169/28 X 1,708,869 4/1929 Buddecke 169/28 2,856,010 10/1958 Brill et a1 l 169/9 2,960,369 11/1960 Goldie 169/9 X 3,350,306 10/1967 Alleton 169/46 X 3,387,662 6/1968 Molgano, .lr...... 169/26 3,392,787 7/1968 Weise 169/26 1 1 June 17, 1975 PrimadExaminer-M. Henson Wood, Jr. Assistant Examiner-Michael Mar Attorney, Agent, or Firm-Charles F. Steininger {57] ABSTRACT A fire extinguishing system for the engine compartment of a motor vehicle in which a generally tubular container, filled with a synergistic mixture of an alkali metal or alkaline earth metal carbonate or bicarbonate and a synthetic metal silicate, is mounted in the compartment, preferably on a side wall or in the air cleaner, a dispersing means is mounted on one or both ends of the container, a propellant means, preferably including a gas impervious piston, a container of a pressurized gas and a spring-loaded puncturing means, is mounted in the container and a flame-actuated ignition means, preferably composed of specific amounts of platinum or palladium in intimate contact with aluminum or magnesium, is operatively attached to the propellant means and disposed about the interior of the compartment 9 Claims, 8 Drawing Figures PATENTEDJUN 17 I975 4 m wow All MOTOR VEHICLE FIRE EXTINGUISHER REFERENCES TO RELATED APPLICATIONS The present application is a continuation-inpart of applications Ser. No. 131,333, filed Apr. 5, 1971 now US. Pat. No. 3,773.111; Ser. No. 400,623, filed Sep. 25, 1973 and Ser. No. 400,640, filed Sep. 25, 1973. all by the present inventor. These prior applications are incorporated herein by reference.

BACKGROUND OF THE INVENTION The present invention relates to fire detection and extinguishing systems for engine compartments of motor vehicles.

Fires in the engine compartments of motor vehicles are significantly increasing due to the use of high compression engines and the added burdens of antipollution devices, automatic chokes and the like. This is often demonstrated by the presence of a first engine after even a minor traffic accident as well as by the in creased use of hand extinguishers in automotive equipment and the urging of fire officials that every auto be equipped with a readily available hand extinguisher. Obviously, hand extinguishers are not a reasonable answer to the problem. First in the engine compartment ofa motor vehicle is usually detected by smoke pouring from beneath the hoodv By the time this is detected, a major conflagration has already occurred and there is little that a hand extinguisher can accomplish at this point. There is, of course, also the delay after detection of the fire for locating and operating the hand extinguisher. Lifting the hood under these circumstances and attempting to extinguish the fire with a hand extinguisher are obviously dangerous. It is therefore highly desirable that an automatic system be provided for the detection and extinguishment of fires in the engine compartment of a motor vehicle.

Many automatic and semiautomatic systems have been proposed for use in motor vehicles. Some of these systems utilize carbon dioxide as the extinguishing agent. However, the problems associated therewith are numerous, including the fact that it is dangerous to have a large high pressure cylinder in the engine com partment or elsewhere in the vehicle and such containers are generally large and bulky if they contain sufficient carbon dioxide to actually cover the entire engine compartment.

Other extinguishing systems utilize liquid extinguishing agents, such as bromotrifluoromethane which is a liquid under pressure in a container and when mixed with air and under reduced pressure becomes a gas. However, such liquids have the distinct disadvantages of again requiring a pressure cylinder of substantial size and that such chemicals are toxic. Liquids, such as carbon tetrachloride, also have well-known disadvantages which militate against their use. Further, nozzles for distributing liquid extinguishing agents are also subject to plugging contamination due to the conditions existing under the hood of an automobile. It is also a known fact that dust, dirt, oil and grease accummulate throughout the engine compartment and many of the proposed extinguishing agents are incapable of extinguishing a grease fire and preventing flashback, which will often occur in oils and greases due to the fact that highly heated metal parts are present.

There are also numerous disadvantages to the detection systems utilized in the prior art extinguishing systems. Many of such systems employ thermally fusible fire detection apparatus. However, such systems have two disadvantages, namely; they require an inordinant number of detectors for proper detection coverage in the protected area and such systems can often be inadvertantly actuated since extremely high temperatures develop in the engine compartment of a motor vehicle, often well above the temperature at which the system is actuated. There are also a number of much more complex systems such as those which have a thermal detector which, in turn, actuates an electrical valve operated from the auto battery, Such complex systems are not only subject to failure because of their intricacy, but such valves and electrical systems can often corrode and become plugged or coated with grease and dirt, thereby rendering them incapable of actuation.

It is therefore an object of the present invention to provide a system for detecting and automatically extin guishing a fire in the engine compartment of a motor vehicle. A further object of the present invention is to provide a system for detecting and extinguishing incipient fires in the engine compartment of a motor vehicle which detects and extinguishes such fire in a matter of seconds. A still further object of the present invention is to provide a system for detecting and extinguishing fires in the engine compartment of a motor vehicle which is responsive to a flame but is not responsive to heat. Another and further object of the present invention is to provide a system for detecting and extinguishing fires in the engine compartment of a motor vehicle wherein, once the fire is extinguished, flashback or reignition is essentially prevented. Yet another object of the present invention is to provide a system for detecting and extinguishing fires in the engine compartment of a motor vehicle wherein cleanup of the extinguishing agent is simple and easy.

SUMMARY OF THE INVENTION The present invention relates to an automatic fire extinguishing apparatus for the engine compartment of a motor vehicle comprising at least one container mounted within the engine compartment and adapted to hold a solid, powder-form fire extinguishing agent at essentially ambient pressure, extinguishing agent distributing means operatively connected with the container to distribute extinguishing agent throughout the engine compartment, propellant means within the container adapted to generate a gas pressure on the fire extinguishing agent sufficient to force the extinguishing agent through the distributing means, and a flameresponsive ignition means resistant to spontaneous ignition at temperatures normally encountered in the engine compartment, operatively to the propellant means to energize the propellant means and cause the propellant means to generate a gas pressure and disposed across the engine compartment above the engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing an extinguishing system in accordance with the present invention mounted in the engine compartment of a motor vehicle;

FIG. 2 is a perspective view showing an extinguishing system in accordance with the present invention mounted in the engine compartment of a motor vehicle;

FIG. 3 is an exploded view showing a cannister assembly and nozzle assembly of an extinguisher for use in accordance with the present invention;

FIGv 4 is a cross-sectional view showing the assembled nozzle assembly;

FIG. 5 is a cross-sectional view taken along the line 5-5 of FIG. 4;

FIG. 6 is a side view of a propellant means and actuator means for use in the extinguisher of the present invention',

FIG. 7 is a top view of the propellant means and actuator means of FIG. 6; and

FIG. 8 is an exploded view of a modified form of the cannister assembly of FIG. 3.

DETAILED DESCRIPTION OF THE INVENTION FIG. 1 of the drawings shows, in phantom, a motor vehicle having an engine compartment 10 formed by fire wall 12, side walls I4, formed by the inside walls of the fender wells, and a hood 16 forming a closure for the top of the engine compartment. There is, of course, mounted within the engine compartment an engine 18. Mounted on the fender wells or side walls 14 of the en gine compartment 10 are fire extinguishing units 20. Fire extinguishing units 20 comprise a cannister assembly 22 and a distributor assembly 24. Leading from the end of cannister 22 opposite the end carrying the distributor means 24 is a flame-responsive sensor or ignition wire 26 which is adapted to respond to and burn as a result of contact with a flame but is resistant to spontaneous ignition at temperatures normally encountered in the engine compartment. The ignition line 26 is held against the fender wells 14 and the fire wall 12 of the engine compartment by means of eyelets or hooks 28.

FIG. 2 of the drawings shows a modified form of extinguishing system in accordance with the present invention. In FIG. 2, a tire extinguisher unit 20 comprises a single cannister assembly 30 having two nozzle assemblies 24 and the ignition line 26 extending from the center of the cannister 30 and disposed in a pattern across the hood 16 of the engine compartment.

The place of mounting of the extinguishing unit 20 and the number of units is optional and depends only upon the space available and whether the location permits the distributing assembly 24 to properly distribute the extinguishing agent throughout the engine compartment. For example, the cannister assembly could be mounted in the air cleaner of the engine 18 if nozzles of the distributing means are pointing radially outwardly. It should also be recognized that when utilizing the extinguisher units of the present invention, the powder-form extinguishing agent is forced outwardly at a sufficiently high pressure and the distributing nozzles distribute the extinguishing agent over a such a wide area that a single extinguishing unit, such as that shown in FIG. 1, will often be adequate. This follows from the fact that the extinguishing agent will rebound from an opposite side wall or from the parts of the engine and thereby result in a general fogging of the entire engine compartment.

FIG. 3 of the drawings shows an exploded view of the cannister assembly 22 and the nozzle assembly 24 of the fire extinguishing system of the present application. In FIG. 3, a main tubular body portion 32 is provided.

Body portion 32 is threaded at its rear end portion 34. Mounted inside tubular body 32, adjacent the front end thereof and resting against a reduced shoulder therein, is frangible disc 36. The tubular body 32 is packed with a dry chemical fire extinguishing agent 38 (hereinafter referred to in greater detail). Thereafter, a piston assembly 40 is positioned in tubular body 32. The rear end of tubular body portion 32 is then closed by means of frangible disc 42 mounted on actuator plate 44. Actuator plate 44 has mounted thereon actuator assembly 46. Actuator plate 44 rests on a shoulder in end cap assembly 48. Cap 48 is screwed on portion 34 of tubular body 32 and sealed by means of O-ring 50. The front end of tubular body 32 is closed by an integrally formed, deflector head portion 52. Head portion 52 directs the extinguishing material 38 downwardly where it exits through mounting head 54, formed as the male portion of a bayonet connection. Mounted within an annular groove in mounting head 54 is O-ring 58 which forms a part of nozzle assembly 24. Nozzle assembly 24 includes 24 includes nozzle base 60, formed as the female portion of the bayonet connection, which mounts on mounting head 54. Nozzle base 60 has hemispherical nozzle supports 62 provided with angularly disposed apertures 64. Passing through apertures 64 are distributing nozzles 66. Distributing nozzles 66 have mounted in their upper ends nozzle deflectors 68 and in their lower ends temporary nozzle seals 70. The free ends of distributing nozzles 66, which pass through apertures 64, have slidably mounted on the outside thereof nozzle retainers 72. Nozzle retainers 72 are press-fit on nozzles 66 in a manner such that nozzles 66 and nozzle retainers 72 are freely movable over a wide angular range about hemispherical supports 62.

FIGS. 4 and 5 of the drawings show the nozzle assembly 24 (FIG. 3) in its assembled condition. The assembly, of course, includes nozzle base 60 having hemispherical projections 62 with apertures 64 formed therein. Passing into and through the apertures 64 is distributing nozzle 66. Distributing nozzle 66 has temporary end cap mounted in one end thereof and nozzle deflector 68 mounted in the opposite end. Distributing nozzle 66 is also provided at its upper end with angularly disposed apertures 74. When pressure is applied to the dry extinguishing agent 38 (FIG. 3) in body 32 of the cannister assembly, the pressurized extinguishing powder is forced outwardly through apertures 74 and the interior of nozzle 66 and this pressure blows cap 70 out the end of nozzle 66. Otherwise, cap 70 provides a seal to prevent grease, moisture and the like from entering the nozzle assembly. Apertures 74 also serve a very distinct purpose. As will be seen from FIGS. 4 and 5, apertures 74 are disposed parallel to the radii of nozzle 66 and offset therefrom. By this placement, the powdered fire extinguishing agent exits through nozzle 66 in a swirling or a vortical motion due to the coaction of and placement of the apertures 74 with respect to deflector 68. This has a critical effect on the distribution of the powdered extinguishing agent over the area to be protected.

FIGS. 6 and 7 show the actuator assembly 46 in detail. Actuator assembly 46 is held in place by actuator brakcet 76. Actuator bracket 76 is provided with a flange portion 78 which extends over and holds pressurized gas bottle 80 in place. Actuator bracket 76 is provided with apertures 82 which fit on posts (not shown) of actuator plate 44. Passing through a central aperture between the posts is a screw 84 which passes into plate 44 to hold actuator bracket 76 in place. Actuator bracket 76 is provided with an aperture 86 which cooperates with an aperture in place 44 to receive pivot pin 88 of the actuator assembly. Mounted on pivot pin 88 is hammer bracket 90. Hammer bracket 90 carries hammer 92 with puncturing pin 94. The puncturing pin 94 is so aligned that it will puncture the seal of gas bottle 80 at an appropriate time. Hammer 92 is manufactured as a separate entity from hammer bracket 90 and is attached thereto by swaging a central post 96. Pivot pin 88 also carries helical, power spring 98 which has one end thereof resting on top of hammer bracket 90 and the other end thereof resting against a post of support plate 44. The solid line outline of hammer bracket 90, hammer 92 and spring 98 show the active or released position of these elements. Shown in dashed lines is the cocked or inactive position of hammer bracket 90, hammer 92 and spring 98. Hammer bracket 90 is held in the cocked position by means of clip 100. Clip 100 is held in place by having two side extensions thereof pass into aperture 102 in the actuator bracket 76 and an aperture in plate 44. Clip 100 is therefore free to rotate or pivot to a limited extent making it possible to align the clip with hammer bracket 90. However, bracket 90 is thereby held in the cocked position by gripping the same between the legs of clip 100 and then wrapping sensor 26 about the free ends of the clip. Thus, it is obvious that the actuator, once cocked, will operate as follows: The sensor 26 will burn, releasing the tension on clip 100. Clip I00 will thereby release hammer bracket 90 which is driven by powder spring 98. In the extreme, hammer bracket 90 will assume the position shown in solid lines with the hammer 92 against the end of gas bottle 80 and the puncturing pin 94 through the seal of gas bottle 80.

FIG. 8 of drawings shows a modified form of the cannister assembly of FIG. 3. It will be apparent from FIG. 8 that the right and left-hand portions of the cannister assembly are mirror images of one another. The basic difference between the cannister of FIG. 8 and that of FIG. 3 is that a single propellant means and actuator assembly 46 is mounted in the center of two half portions 104 and 106, respectively, of the cannister body. The assembly 46 may be mounted in a sleeve (not shown) which is internally threaded to receive the threaded ends of sections 104 and 106 of the cannister body. Otherwise, the parts of the cannister assembly of FIG. 8 are duplicates of those of FIG. 3. Accordingly, the remaining elements have been numbered with numbers corresponding to those in FIG. 3 except that the designations a and b have been utilized in order to distinguish elements in the two endsv It is also quite obvious that the nozzle assembly 24 is mounted on each end of the cannister assembly of FIG. 8.

The cannister assembly and the nozzle assembly are preferably made of a material having a high degree of toughness, impact strength, heat resistance and dimensional stability and good electrical properties. While there are a number of materials which can be utilized, the preferred material is Lexan IOl manufactured by the General Electric Company. This material is a thermoplastic polycarbonate resin suitable for use in molded or extruded structures and exhibits all of the properties specified above.

The sensor should be selected on the basis of the con ditions to which it is subjected. The primary requisite is that the sensor should not be spontaneously ignited by heat alone but will be ignited and burn rapidly when a flame strikes it. A desirable sensor wire is one having about to 20 parts by volume of a noble metal, such as, platinum or palladium and 20 to 80 parts by volume of a second metal, such as, magnesium or aluminum. A particularly preferred material is a wire-type fuse known as PYROFUZE manufactured by Pyrofuze Co. of Mount Vernon, New York. This sensor wire is a coaxially braided material having an aluminum core and a palladium shell. Platinum may also be used as the shell material. The wire normally will not ignite or burn at radiant heat temperatures as high as 1,200F but will ignite instantaneously and burn rapidly, at a rate of about 0.9 foot per second, when contacted by a flame.

The frangible discs utilized in accordance with the present invention are a laminate of papcr-polycthylenc aluminum foil-polyvinyl.

The nozzle seals are preferably of molded plastic lined with a laminate of paper and aluminum foil.

The pressurized gas bottle is preferably a bottle containing liquified CO A suitable CO cartridge is the type manufactured for Mae West life jackets. This component is designated by the US. Military as MIL- C-60IB, Type I.

The preferred fire extinguishing material for use in the present invention not only rapidly extinguishes the original flame but holds this condition and prevents or abates flashback or reignitionv This is detailed in copending applications Ser, Nos. 400,623 and 400,640 and reference is made thereto. The tire extinguishing agent of the present invention is a synergistic mixture of about 50 to 95% by weight of an alkali metal carbon ate, an alkaline earth metal carbonate. an alkali metal bicarbonate or an alkaline earth metal bicarbonate and about 50 to 5% by weight of a metal silicate. Because of its availability, effectiveness and freedom from toxicity, the preferred carbonate is sodium bicarbonate. Preferably, the sodium bicarbonate is present in amounts between about and 60% by weight of the composition. Specifically, the most desirable composition contains about 78% to 80% by weight of sodium bicarbonate. The metal silicate is prefer-ably a nontoxic alkali metal or alkaline earth metal silicate and of a substantially pure character, such as, a material manufactured by precipitation. A highly effective silicate for use accordance with the present invention is Silene L," manufactured by Pittsburgh Plate Glass Company, Pittsburgh, Pennsylvania. This material is a precipitated calcium silicate and has an approximate analysis of CaO 19% and Si0 57%, and a loss on ignition of about 14%. It has a specific gravity of about 2.] and bulk density of about 15 to [6 pounds per cubic foot. The preferred range of silicate is in the amount of 15 to 40% by weight and. specifically, the most effective has been found to be about 19% to 20% by weight. The composition may also include minor amounts of up to about 5% by weight of conventional dcsiccants, lubricants, adsorbents and the like. Suitable materials of this character include calcium chloride, diatomaceous earth, silica gel. calcium stearate, etc. and preferably are present in an amount of about 3% Calcium stearate is a preferred desiccant. However, this last component is not necessary to the synergistic effect of the mixture of the present invention nor to its freeflowing properties. It has been found in accordance with the present invention that the mixture of bicarbonate and silicate has free-flowing characteristics making its discharge from a suitable extinguishing apparatus superior to most conventional extinguishing agents. It also resists stratification in storage and in the extinguishing apparatus. The mixture is also capable of withstanding ex treme temperatures without deterioration, thereby providing long shelf life and useful without recharging or replacement and is relatively resistant to moisture deterioration. The dry, chemical fire extinguishing agent of the present invention is packed in body 24 of the can nister between frangible discs 36 and 42 by vibration of the cannister and is the only known dry, chemical extinguishing agent which can be loaded in this manner. This packing of the extinguishing agent has been approved by Underwriters Laboratories and, as indicated, is the only material approved for packing in this manner. This, of course, also contributes to non- Stratification.

While specific examples and structures have been described and illustrated herein, it is to be understood that modifications thereof will be obvious to one skilled in the art. Accordingly, the present invention is to be limited only in accordance with the appended claims.

I claim:

I. A fire extinguishing system for the engine com partment of a motor vehicle, comprising, a generally cylindrical container mounted on the interior of said compartment, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said compartment, pro pellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means and including gasimpermeable piston means mounted adjacent said extinguishing agent and in gas-tight relation with the walls of said container and flame-responsive ignition means resistant to ignition by heat generated in said compartment, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said compartment.

2. A system in accordance with claim 1 wherein the propellant means includes a container of a gas under pressure and puncturing means for puncturing said container.

3. A fire extinguishing system for the engine compartment of a motor vehicle, comprising, a container mounted in said compartment, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on each end of said container to distribute said extinguishing agent throughout said compartment, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and flame-responsive ignition means resistant to ignition by heat generated in said compartment, ope ratively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said compartment.

4. A fire extinguishing system for the engine compartment of a motor vehicle, comprising a container mounted in said compartment, a solid, powder-form fire extinguishing agent disposed in said container comprising a metal carbonate selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, alkaline earth metal carbonates, alkaline earth metal bicarbonates and mixtures thereof, in a major amount of about 50 to 95% by weight, and a synthetic metal silicate, in a minor amount of about 50 to 5% by weight and sufficient to form an air-impermeable coat ing on the burning surface to which it is applied and prevent reignition of an extinguished flame for at least 10 minutes, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said compartment, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and flame-responsive ignition means resistant to ignition by heat generated in said compartment, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said compartment.

5. A system in accordance with claim 4 wherein the container is mounted on an interior side wall of the compartment.

6. A system in accordance with claim 4 wherein the container is mounted in the air cleaner of the engine and the distributing means includes radially disposed nozzles.

7. A fire extinguishing system for the engine compartment of a motor vehicle, comprising, a container mounted in said compartment, a solid, power-form fire extinguishing agent disposed in said container, dispersing means powder-form mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and wiretype, flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet and comprising 20 to by volume of a metal selected from the group consisting of platinum and palladium and 80 to 20% by volume of a metal selected from the group consisting of aluminum and magnesium.

8. A system in accordance with claim 7 wherein the container is mounted on an interior side wall of the compartment.

9. A system in accordance with claim 7 wherein the container is mounted in the air cleaner of the engine and the distributing means includes radially disposed nozzles. 

1. A fire extinguishing system for the engine compartment of a motor vehicle, comprising, a generally cylindrical container mounted on the interior of said compartment, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said compartment, propellant means in said container adapted to geNerate a gas pressure sufficient to force said extinguishing agent through said distributing means and including gas-impermeable piston means mounted adjacent said extinguishing agent and in gas-tight relation with the walls of said container and flame-responsive ignition means resistant to ignition by heat generated in said compartment, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said compartment.
 2. A system in accordance with claim 1 wherein the propellant means includes a container of a gas under pressure and puncturing means for puncturing said container.
 3. A fire extinguishing system for the engine compartment of a motor vehicle, comprising, a container mounted in said compartment, a solid, powder-form fire extinguishing agent disposed in said container, dispersing means operatively mounted on each end of said container to distribute said extinguishing agent throughout said compartment, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and flame-responsive ignition means resistant to ignition by heat generated in said compartment, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said compartment.
 4. A fire extinguishing system for the engine compartment of a motor vehicle, comprising a container mounted in said compartment, a solid, powder-form fire extinguishing agent disposed in said container comprising a metal carbonate selected from the group consisting of alkali metal carbonates, alkali metal bicarbonates, alkaline earth metal carbonates, alkaline earth metal bicarbonates and mixtures thereof, in a major amount of about 50 to 95% by weight, and a synthetic metal silicate, in a minor amount of about 50 to 5% by weight and sufficient to form an air-impermeable coating on the burning surface to which it is applied and prevent reignition of an extinguished flame for at least 10 minutes, dispersing means operatively mounted on said container to distribute said extinguishing agent throughout said compartment, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and flame-responsive ignition means resistant to ignition by heat generated in said compartment, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said compartment.
 5. A system in accordance with claim 4 wherein the container is mounted on an interior side wall of the compartment.
 6. A system in accordance with claim 4 wherein the container is mounted in the air cleaner of the engine and the distributing means includes radially disposed nozzles.
 7. A fire extinguishing system for the engine compartment of a motor vehicle, comprising, a container mounted in said compartment, a solid, power-form fire extinguishing agent disposed in said container, dispersing means powder-form mounted on said container to distribute said extinguishing agent throughout said cabinet, propellant means in said container adapted to generate a gas pressure sufficient to force said extinguishing agent through said distributing means, and wire-type, flame-responsive ignition means resistant to ignition by heat generated in said cabinet, operatively connected to said propellant means to actuate said propellant means and cause it to generate gas pressure and disposed about said cabinet and comprising 20 to 80% by volume of a metal selected from the group consisting of platinum and palladium and 80 to 20% by volume of a metal selected from the group consisting of aluminum and magnesium.
 8. A system in accordance with claim 7 wherein the container is mounted on an interior side wall of the compartment.
 9. A system in accOrdance with claim 7 wherein the container is mounted in the air cleaner of the engine and the distributing means includes radially disposed nozzles. 